Photoresist defect reduction system and method

ABSTRACT

A system and method for reducing defects in photoresist processing is provided. An embodiment comprises cleaning the photoresist after development using an alkaline environment. The alkaline environment may comprise a neutral solvent and an alkaline developer. The alkaline environment will modify the attraction between residue leftover from development and a surface of the photoresist such that the surfaces repel each other, making the removal of the residue easier. By removing more residue, there will be fewer defects in the photolithographic process.

This application is a continuation of U.S. patent application Ser. No. 13/790,057, entitled “Photoresist Defect Reduction System and Method,” filed on Mar. 8, 2013, which application is incorporated herein by reference.

BACKGROUND

As consumer devices have gotten smaller and smaller in response to consumer demand, the individual components of these devices have necessarily decreased in size as well. Semiconductor devices, which make up a major component of devices such as mobile phones, computer tablets, and the like, have been pressured to become smaller and smaller, with a corresponding pressure on the individual devices (e.g., transistors, resistors, capacitors, etc.) within the semiconductor devices to also be reduced in size.

One enabling technology that is used in the manufacturing processes of semiconductor devices is the use of photolithographic materials. Such materials are applied to a surface and then exposed to an energy that has itself been patterned. Such an exposure modifies the chemical and physical properties of the exposed regions of the photolithographic material. This modification, along with the lack of modification in regions of the photolithographic material that were not exposed, can be exploited to remove one region without removing the other.

However, as the size of individual devices has decreased, process windows for photolithographic processing as become tighter and tighter. As such, advances in the field of photolithographic processing have been necessitated in order to keep up the ability to scale down the devices, and further improvements are needed in order to meet the desired design criteria such that the march towards smaller and smaller components may be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present embodiments, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a photoresist on a semiconductor substrate in accordance with an embodiment;

FIG. 2 illustrates an exposure of the photoresist in accordance with an embodiment;

FIGS. 3A-3B illustrate a development of the photoresist in accordance with an embodiment;

FIGS. 4A-4B illustrate a removal of the developer and a residue in accordance with an embodiment;

FIGS. 5A-5C illustrate an alkaline environment for the removal of the residue in accordance with an embodiment; and

FIGS. 6A-6B illustrate test results that illustrate the effects of using an alkaline environment to remove the residue in accordance with an embodiment.

Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the present embodiments are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the disclosed subject matter, and do not limit the scope of the different embodiments.

Embodiments will be described with respect to a specific context, namely a photoresist cleaning process utilized in the manufacturing of semiconductor devices. Other embodiments may also be applied, however, to other cleaning processes of other materials.

With reference now to FIG. 1, there is shown a semiconductor device 100 with a substrate 101, active devices 103 on the substrate 101, an interlayer dielectric (ILD) layer 105 over the active devices 103, metallization layers 107 over the ILD layer 105, a layer to be patterned 109 over the ILD layer 105, and a photoresist 111 over the layer to be patterned 109. The substrate 101 may comprise bulk silicon, doped or undoped, or an active layer of a silicon-on-insulator (SOI) substrate. Generally, an SOI substrate comprises a layer of a semiconductor material such as silicon, germanium, silicon germanium, SOI, silicon germanium on insulator (SGOI), or combinations thereof. Other substrates that may be used include multi-layered substrates, gradient substrates, or hybrid orientation substrates.

The active devices 103 are represented in FIG. 1 as a single transistor. However, as one of skill in the art will recognize, a wide variety of active devices such as capacitors, resistors, inductors and the like may be used to generate the desired structural and functional requirements of the design for the semiconductor device 100. The active devices 103 may be formed using any suitable methods either within or else on the surface of the substrate 101.

The ILD layer 105 may comprise a material such as boron phosphorous silicate glass (BPSG), although any suitable dielectrics may be used for either layer. The ILD layer 105 may be formed using a process such as PECVD, although other processes, such as LPCVD, may alternatively be used. The ILD layer 105 may be formed to a thickness of between about 100 Å and about 3,000 Å.

The metallization layers 107 are formed over the substrate 101, the active devices 103, and the ILD layer 105 and are designed to connect the various active devices 103 to form functional circuitry. While illustrated in FIG. 1 as a single layer, the metallization layers 107 are formed of alternating layers of dielectric and conductive material and may be formed through any suitable process (such as deposition, damascene, dual damascene, etc.). In an embodiment there may be four layers of metallization separated from the substrate 101 by the ILD layer 105, but the precise number of metallization layers 107 is dependent upon the design of the semiconductor device 100.

A layer to be patterned 109 or otherwise processed using the photoresist 111 is formed over the metallization layers 107. The layer to be patterned 109 may be an upper layer of the metallization layers 107 or else may be a dielectric layer (such as a passivation layer) formed over the metallization layers 107. In an embodiment in which the layer to be patterned 109 is a metallization layer, the layer to be patterned 109 may be formed of a conductive material using processes similar to the processes used for the metallization layers (e.g., damascene, dual damascene, deposition, etc.). Alternatively, if the layer to be patterned 109 is a dielectric layer the layer to be patterned 109 may be formed of a dielectric material using such processes as deposition, oxidation, or the like.

However, as one of ordinary skill in the art will recognize, while materials, processes, and other details are described in the embodiments, these details are merely intended to be illustrative of embodiments, and are not intended to be limiting in any fashion. Rather, any suitable layer, made of any suitable material, by any suitable process, and any suitable thickness, may alternatively be used. All such layers are fully intended to be included within the scope of the embodiments.

The photoresist 111 is applied to the layer to be patterned 109. In an embodiment the photoresist 111 includes a polymer resin along with one or more photoactive compounds (PACs) in a solvent. In an embodiment the polymer resin may comprise a hydrocarbon structure (such as a alicyclic hydrocarbon structure) that contains one or more groups that will decompose (e.g., acid leaving groups) or otherwise react when mixed with acids, bases, or free radicals generated by the PACs (as further described below). In an embodiment the hydrocarbon structure comprises a repeating unit that forms a skeletal backbone of the polymer resin. This repeating unit may include acrylic esters, methacrylic esters, crotonic esters, vinyl esters, maleic diesters, fumaric diesters, itaconic diesters, (meth)acrylonitrile, (meth)acrylamides, styrenes, vinyl ethers, combinations of these, or the like.

Specific structures which may be utilized for the repeating unit of the hydrocarbon structure include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, acetoxyethyl acrylate, phenyl acrylate, 2-hydroxyethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-(2-methoxyethoxyl)ethyl acrylate, cyclohexyl acrylate, benzyl acrylate, 2-alkyl-2-adamantyl(meth)acrylate or dialkyl(1-adamantyl)methyl(meth)acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, acetoxyethyl methacrylate, phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-(2-methoxyethoxyl)ethyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, 3-acetoxy-2-hydroxypropyl methacrylate, 3-chloroacetoxy-2-hydroxypropyl methacrylate, butyl crotonate, hexyl crotonate and the like. Examples of the vinyl esters include vinyl acetate, vinyl propionate, vinyl butylate, vinyl methoxyacetate, vinyl benzoate, dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, acrylamide, methyl acrylamide, ethyl acrylamide, propyl acrylamide, n-butyl acrylamide, tert-butyl acrylamide, cyclohexyl acrylamide, 2-methoxyethyl acrylamide, dimethyl acrylamide, diethyl acrylamide, phenyl acrylamide, benzyl acrylamide, methacrylamide, methyl methacrylamide, ethyl methacrylamide, propyl methacrylamide, n-butyl methacrylamide, tert-butyl methacrylamide, cyclohexyl methacrylamide, 2-methoxyethyl methacrylamide, dimethyl methacrylamide, diethyl methacrylamide, phenyl methacrylamide, benzyl methacrylamide, methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxyethyl vinyl ether, dimethylaminoethyl vinyl ether and the like. Examples of the styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, butyl styrene, methoxy styrene, butoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, vinyl methyl benzoate, α-methyl styrene, maleimide, vinylpyridine, vinylpyrrolidone, vinylcarbazole, combinations of these, or the like.

In an embodiment the repeating unit of the hydrocarbon structure may also have either a monocyclic or a polycyclic hydrocarbon structure substituted into it, or else the monocyclic or polycyclic hydrocarbon structure may be the repeating unit, in order to form an alicyclic hydrocarbon structure. Specific examples of monocyclic structures that may be used include bicycloalkane, tricycloalkane, tetracycloalkane, cyclopentane, cyclohexane, or the like. Specific examples of polycyclic structures that may be used include cycloalkane, adamantine, adamantine, norbornane, isobornane, tricyclodecane, tetracycododecane, or the like.

The group which will decompose, otherwise known as a leaving group or, in an embodiment in which the PAC is a photoacid generator, an acid leaving group is attached to the hydrocarbon structure so that it will react with the acids/bases/free radicals generated by the PACs during exposure. In an embodiment the group which will decompose may be a carboxylic acid group, a fluorinated alcohol group, a phenolic alcohol group, a sulfonic group, a sulfonamide group, a sulfonylimido group, an (alkylsulfonyl) (alkylcarbonyl)methylene group, an (alkylsulfonyl)(alkyl-carbonyl)imido group, a bis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imido group, a bis(alkylsylfonyl)methylene group, a bis(alkylsulfonyl)imido group, a tris(alkylcarbonyl methylene group, a tris(alkylsulfonyl)methylene group, combinations of these, or the like. Specific groups that may be utilized for the fluorinated alcohol group include fluorinated hydroxyalkyl groups, such as a hexafluoroisopropanol group. Specific groups that may be utilized for the carboxylic acid group include acrylic acid groups, methacrylic acid groups, or the like.

In an embodiment the polymer resin may also comprise other groups attached to the hydrocarbon structure that help to improve a variety of properties of the polymerizable resin. For example, inclusion of a lactone group to the hydrocarbon structure assists to reduce the amount of line edge roughness after the photoresist 111 has been developed, thereby helping to reduce the number of defects that occur during development. In an embodiment the lactone groups may include rings having five to seven members, although any suitable lactone structure may alternatively be used for the lactone group.

The polymer resin may also comprise groups that can assist in increasing the adhesiveness of the photoresist 111 to underlying structures (e.g., the layer to be patterned 109). In an embodiment polar groups may be used to help increase the adhesiveness, and polar groups that may be used in this embodiment include hydroxyl groups, cyano groups, or the like, although any suitable polar group may alternatively be utilized.

Optionally, the polymer resin may further comprise one or more alicyclic hydrocarbon structures that do not also contain a group which will decompose. In an embodiment the hydrocarbon structure that does not contain a group which will decompose may include structures such as 1-adamantyl(meth)acrylate, tricyclodecanyl(meth)acrylate, cyclohexayl(meth)acrylate, combinations of these, or the like.

Additionally, the photoresist 111 also comprises one or more PACs. The PACs may be photoactive components such as photoacid generators, photobase generators, free-radical generators, or the like, and the PACs may be positive-acting or negative-acting. In an embodiment in which the PACs are a photoacid generator, the PACs may comprise halogenated triazines, onium salts, diazonium salts, aromatic diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonate, oxime sulfonate, disulfone, o-nitrobenzylsulfonate, sulfonated esters, halogenerated sulfonyloxy dicarboximides, diazodisulfones, α-cyanooxyamine-sulfonates, imidesulfonates, ketodiazosulfones, sulfonyldiazoesters, 1,2-di(arylsulfonyl)hydrazines, nitrobenzyl esters, and the s-triazine derivatives, suitable combinations of these, and the like.

Specific examples of photoacid generators that may be used include α.-(trifluoromethylsulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarbo-ximide (MDT), N-hydroxy-naphthalimide (DDSN), benzoin tosylate, t-butylphenyl-α-(p-toluenesulfonyloxy)-acetate and t-butyl-α-(p-toluenesulfonyloxy)-acetate, triarylsulfonium and diaryliodonium hexafluoroantimonates, hexafluoroarsenates, trifluoromethanesulfonates, iodonium perfluorooctanesulfonate, N-camphorsulfonyloxynaphthalimide, N-pentafluorophenylsulfonyloxynaphthalimide, ionic iodonium sulfonates such as diaryl iodonium (alkyl or aryl) sulfonate and bis-(di-t-butylphenyl)iodonium camphanylsulfonate, perfluoroalkanesulfonates such as perfluoropentanesulfonate, perfluorooctanesulfonate, perfluoromethanesulfonate, aryl (e.g., phenyl or benzyl) triflates such as triphenylsulfonium triflate or bis-(t-butylphenyl)iodonium triflate; pyrogallol derivatives (e.g., trimesylate of pyrogallol), trifluoromethanesulfonate esters of hydroxyimides, α,α′-bis-sulfonyl-diazomethanes, sulfonate esters of nitro-substituted benzyl alcohols, naphthoquinone-4-diazides, alkyl disulfones, and the like.

In an embodiment in which the PACs are a free-radical generator, the PACs may comprise n-phenylglycine, aromatic ketones such as benzophenone, N,N′-tetramethyl-4,4′-diaminobenzophenone, N,N′-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzo-phenone, 3,3′-dimethyl-4-methoxybenzophenone, p,p′-bis(dimethylamino)benzo-phenone, p,p′-bis(diethylamino)-benzophenone, anthraquinone, 2-ethylanthraquinone, naphthaquinone and phenanthraquinone, benzoins such as benzoin, benzoinmethylether, benzoinethylether, benzoinisopropylether, benzoin-n-butylether, benzoin-phenylether, methylbenzoin and ethybenzoin, benzyl derivatives such as dibenzyl, benzyldiphenyldisulfide and benzyldimethylketal, acridine derivatives such as 9-phenylacridine and 1,7-bis(9-acridinyl)heptane, thioxanthones such as 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone and 2-isopropylthioxanthone, acetophenones such as 1,1-dichloroacetophenone, p-t-butyldichloro-acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, and 2,2-dichloro-4-phenoxyacetophenone, 2,4,5-triarylimidazole dimers such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di-(m-methoxyphenyl imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer and 2-(p-methylmercaptophenyl)-4,5-diphenylimidazole dimmer, suitable combinations of these, or the like.

In an embodiment in which the PACs are a photobase generator, the PACs may comprise quaternary ammonium dithiocarbamates, α aminoketones, oxime-urethane containing molecules such as dibenzophenoneoxime hexamethylene diurethan, ammonium tetraorganylborate salts, and N-(2-nitrobenzyloxycarbonyl) cyclic amines, suitable combinations of these, or the like. However, as one of ordinary skill in the art will recognize, the chemical compounds listed herein are merely intended as illustrated examples of the PACs and are not intended to limit the embodiments to only those PACs specifically described. Rather, any suitable PAC may alternatively be utilized, and all such PACs are fully intended to be included within the scope of the present embodiments.

The individual components of the photoresist 111 may be placed into a solvent in order to aid in the mixing and placement of the photoresist 111. To aid in the mixing and placement of the photoresist 111, the solvent is chosen at least in part based upon the materials chosen for the polymer resin as well as the PACs. In particular, the solvent is chosen such that the polymer resin and the PACs can be evenly dissolved into the solvent and dispensed upon the layer to be patterned 109.

In an embodiment the solvent may be an organic solvent, and may comprise any suitable solvent such as ketones, alcohols, polyalcohols, ethers, glycol ethers, cyclic ethers, aromatic hydrocarbons, esters, propionates, lactates, lactic esters, alkylene glycol monoalkyl ethers, alkyl lactates, alkyl alkoxypropionates, cyclic lactones, monoketone compounds that contain a ring, alkylene carbonates, alkyl alkoxyacetate, alkyl pyruvates, ethylene glycol alkyl ether acetates, diethylene glycols, propylene glycol alkyl ether acetates, alkylene glycol alkyl ether esters, alkylene glycol monoalkyl esters, or the like.

Specific examples of materials that may be used as the solvent for the photoresist 111 include, acetone, methanol, ethanol, toluene, xylene, 4-hydroxy-4-methyl-2-pentatone, tetrahydrofuran, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, ethylene glycol dimethyl ether, ethylene glycol dimethyl ether, ethylene glycol methylethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol, diethylene glycol monoacetate, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol ethylmethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-2-methylbutanate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl acetate, butyl acetate, methyl lactate and ethyl lactate, propylene glycol, propylene glycol monoacetate, propylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monopropyl methyl ether acetate, propylene glycol monobutyl ether acetate, propylene glycol monobutyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether propionate, propylene glycol methyl ether adcetate, proplylene glycol ethyl ether acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propyl lactate, and butyl lactate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, methyl 3-ethoxypropionate, and ethyl 3-methoxypropionate, β-propiolactone, β-butyrolactone, γ-butyrolactone, α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-octanoic lactone, α-hydroxy-γ-butyrolactone, 2-butanone, 3-methylbutanone, pinacolone, 2-pentanone, 3-pentanone, 4-methyl-2-pentanone, 2-methyl-3-pentanone, 4,4-dimethyl-2-pentanone, 2,4-dimethyl-3-pentanone, 2,2,4,4-tetramethyl-3-pentanone, 2-hexanone, 3-hexanone, 5-methyl-3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-methyl-3-heptanone, 5-methyl-3-heptanone, 2,6-dimethyl-4-heptanone, 2-octanone, 3-octanone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone, 3-decanone, 4-decanone, 5-hexene-2-one, 3-pentene-2-one, cyclopentanone, 2-methylcyclopentanone, 3-methylcyclopentanone, 2,2-dimethylcyclopentanone, 2,4,4-trimethylcyclopentanone, cyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 4-ethylcyclohexanone, 2,2-dimethylcyclohexanone, 2,6-dimethylcyclohexanone, 2,2,6-trimethylcyclohexanone, cycloheptanone, 2-methylcycloheptanone, 3-methylcycloheptanone, pylene carbonate, vinylene carbonate, ethylene carbonate, and butylene carbonate, acetate-2-methoxyethyl, acetate-2-ethoxyethyl, acetate-2-(2-ethoxyethoxyl)ethyl, acetate-3-methoxy-3-methylbutyl, acetate-1-methoxy-2-propyl, dipropylene glycol, monomethylether, monoethylether, monopropylether, monobutylether, monophenylether, dipropylene glycol monoacetate, dioxane, methyl acetate, ethyl acetate, butyl acetate, methyl puruvate, ethyl puruvate, propyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, n-methylpyrrolidone (NMP), 2-methoxyethyl ether (diglyme), ethylene glycol monom-ethyl ether, propylene glycol monomethyl ether; methyl proponiate, ethyl proponiate and ethyl ethoxy proponiate, methylethyl ketone, cyclohexanone, 2-heptanone, carbon dioxide, cyclopentatone, cyclohexanone, ethyl 3-ethocypropionate, ethyl lactate, propylene glycol methyl ether acetate (PGMEA), methylene cellosolve, butyle acetate, and 2-ethoxyethanol, N-methylformamide, N,N-dimethylformamide, N-methylformanilide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, benzyl ethyl ether, dihexyl ether, acetonylacetone, isophorone, caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate, phenyl cellosolve acetate, or the like.

However, as one of ordinary skill in the art will recognize, the materials listed and described above as examples of materials that may be utilized for the solvent component of the photoresist 111 are merely illustrative and are not intended to limit the embodiments. Rather, any suitable material that may dissolve the polymer resin and the PACs may alternatively be utilized to help mix and apply the photoresist 111. All such materials are fully intended to be included within the scope of the embodiments.

Additionally, while individual ones of the above described materials may be used as the solvent for the photoresist 111, in alternative embodiments more than one of the above described materials may be utilized. For example, the solvent may comprise a combination mixture of two or more of the materials described. All such combinations are fully intended to be included within the scope of the embodiments.

Optionally, a cross-linking agent may also be added to the photoresist 111. The cross-linking agent reacts with the polymer resin within the photoresist 111 after exposure, assisting in increasing the cross-linking density of the photoresist, which helps to improve the resist pattern and resistance to dry etching. In an embodiment the cross-linking agent may be an melamine based agent, a urea based agent, ethylene urea based agent, propylene urea based agent, glycoluril based agent, an aliphatic cyclic hydrocarbon having a hydroxyl group, a hydroxyalkyl group, or a combination of these, oxygen containing derivatives of the aliphatic cyclic hydrocarbon, glycoluril compounds, etherified amino resins, combinations of these, or the like.

Specific examples of materials that may be utilized as a cross-linking agent include melamine, acetoguanamine, benzoguanamine, urea, ethylene urea, or glycoluril with formaldehyde, glycoluril with a combination of formaldehyde and a lower alcohol, hexamethoxymethylmelamine, bismethoxymethylurea, bismethoxymethylbismethoxyethylene urea, tetramethoxymethylglycoluril, and tetrabutoxymethylglycoluril, mono-, di-, tri-, or tetra-hydroxymethylated glycoluril, mono-, di-, tri-, and/or tetra-methoxymethylated glycoluril, mono-, di-, tri-, and/or tetra-ethoxymethylated glycoluril, mono-, di-, tri-, and/or tetra-propoxymethylated glycoluril, and mono-, di-, tri-, and/or tetra-butoxymethylated glycoluril, 2,3-dihydroxy-5-hydroxymethylnorbornane, 2-hydroxy-5,6-bis(hydroxymethyl)norbornane, cyclohexanedimethanol, 3,4,8(or 9)-trihydroxytricyclodecane, 2-methyl-2-adamantanol, 1,4-dioxane-2,3-diol and 1,3,5-trihydroxycyclohexane, tetramethoxymethyl glycoluril, methylpropyltetramethoxymethyl glycoluril, and methylphenyltetramethoxymethylglycoluril, 2,6-bis(hydroxymethyl)p-cresol, N-methoxymethyl- or N-butoxymethyl-melamine. Additionally, compounds obtained by reacting formaldehyde, or formaldehyde and lower alcohols with amino group-containing compounds, such as melamine, acetoguanamine, benzoguanamine, urea, ethylene urea and glycoluril, and substituting the hydrogen atoms of the amino group with hydroxymethyl group or lower alkoxymethyl group, examples being hexamethoxymethylmelamine, bismethoxymethyl urea, bismethoxymethylbismethoxyethylene urea, tetramethoxymethyl glycoluril and tetrabutoxymethyl glycoluril, copolymers of 3-chloro-2-hydroxypropyl methacrylate and methacrylic acid, copolymers of 3-chloro-2-hydroxypropyl methacrylate and cyclohexyl methacrylate and methacrylic acid, copolymers of 3-chloro-2-hydroxypropyl methacrylate and benzyl methacrylate and methacrylic acid, bisphenol A-di(3-chloro-2-hydroxypropyl)ether, poly(3-chloro-2-hydroxypro-pyl)ether of a phenol novolak resin, pentaerythritol tetra(3-chloro-2-hydroxypropyl)ether, trimethylolmethane tri(3-chloro-2-hydroxypropyl)ether phenol, bisphenol A-di(3-acetoxy-2-hydroxypropyl)ether, poly(3-acetoxy-2-hydroxypropyl)ethe-r of a phenol novolak resin, pentaerythritol tetra(3-acetoxy-2-hydroxyprop-yl)ether, pentaerythritol poly(3-chloroacetoxy-2-hydroxypropyl)ether, trimethylolmethane tri(3-acetoxy-2-hydroxypropyl)ether, combinations of these, or the like.

In addition to the polymer resins, the PACs, the solvents, and the cross-linking agents, the photoresist 111 may also include a number of other additives that will assist the photoresist 111 obtain the highest resolution. For example, the photoresist 111 may also include surfactants in order to help improve the ability of the photoresist 111 to coat the surface on which it is applied. In an embodiment the surfactants may include nonionic surfactants, polymers having fluorinated aliphatic groups, surfactants that contain at least one fluorine atom and/or at least one silicon atom, polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters.

Specific examples of materials that may be used as surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenol ether, polyoxyethylene nonyl phenol ether, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, polyethylene glycol distearate, polyethylene glycol dilaurate, polyethylene glycol, polypropylene glycol, polyoxyethylenestearyl ether and polyoxyethylene cetyl ether; fluorine containing cationic surfactants, fluorine containing nonionic surfactants, fluorine containing anionic surfactants, cationic surfactants and anionic surfactants, polyethylene glycol, polypropylene glycol, polyoxyethylene cetyl ether, combinations of these, or the like.

Another additive that may be added to the photoresist 111 is a quencher, which may be utilized to inhibit diffusion of the generated acids/bases/free radicals within the photoresist, which helps the resist pattern configuration as well as to improve the stability of the photoresist 111 over time. In an embodiment the quencher is an amine such as a second lower aliphatic amine, a tertiary lower aliphatic amine, or the like. Specific examples of amines that may be used include trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, tripentylamine, diethanolamine, and triethanolamine, alkanolamine, combinations of these, or the like.

Alternatively, an organic acid may be utilized as the quencher. Specific embodiments of organic acids that may be utilized include malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, phosphorous oxo acid and its derivatives such as phosphoric acid and derivatives thereof such as its esters, such as phosphoric acid, phosphoric acid di-n-butyl ester and phosphoric acid diphenyl ester; phosphonic acid and derivatives thereof such as its ester, such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester; and phosphinic acid and derivatives thereof such as its esters, including phosphinic acid and phenylphosphinic acid.

Another additive that may be added to the photoresist 111 is a stabilizer, which assists in preventing undesired diffusion of the acids generated during exposure of the photoresist 111. In an embodiment the stabilizer may include nitrogenous compounds such as aliphatic primary, secondary, and tertiary amines, cyclic amines such as piperidines, pyrrolidines, morpholines, aromatic heterocycles such as pyridines, pyrimidines, purines, imines such as diazabicycloundecene, guanidines, imides, amides, and others. Alternatively, ammonium salts may also be used for the stabilizer, including ammonium, primary, secondary, tertiary, and quaternary alkyl- and arylammonium salts of alkoxides including hydroxide, phenolates, carboxylates, aryl and alkyl sulfonates, sulfonamides, and others. Other cationic nitrogenous compounds including pyridinium salts and salts of other heterocyclic nitrogenous compounds with anions such as alkoxides including hydroxide, phenolates, carboxylates, aryl and alkyl sulfonates, sulfonamides, and the like may also be employed.

Yet another additive that may be added to the photoresist 111 may be a dissolution inhibitor in order to help control dissolution of the photoresist 111 during development. In an embodiment bile-salt esters may be utilized as the dissolution inhibitor. Specific examples of materials that may be utilized include cholic acid (IV), deoxycholic acid (V), lithocholic acid (VI), t-butyl deoxycholate (VII), t-butyl lithocholate (VIII), and t-butyl-3-α-acetyl lithocholate (IX).

Another additive that may be added to the photoresist 111 may be a plasticizer. Plasticizers may be used to reduce delamination and cracking between the photoresist 111 and underlying layers (e.g., the layer to be patterned 109) and may comprise monomeric, oligomeric, and polymeric plasticizers such as oligo-anpolyethyleneglycol ethers, cycloaliphatic esters, and non-acid reactive steroidally-derived materials. Specific examples of materials that may be used for the plasticizer include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerine and the like.

Yet another additive that may be added include a coloring agent, which helps observers examine the photoresist 111 and find any defects that may need to be remedied prior to further processing. In an embodiment the coloring agent may be either a triarylmethane dye or, alternatively, may be a fine particle organic pigment. Specific examples of materials that may be used as coloring agents include crystal violet, methyl violet, ethyl violet, oil blue #603, Victoria Pure Blue BOH, malachite green, diamond green, phthalocyanine pigments, azo pigments, carbon black, titanium oxide, brilliant green dye (C. I. 42020), Victoria Pure Blue FGA (Linebrow), Victoria BO (Linebrow) (C. I. 42595), Victoria Blue BO (C. I. 44045) rhodamine 6G (C. I. 45160), Benzophenone compounds such as 2,4-dihydroxybenzophenone and 2,2′,4,4′-tetrahydroxybenzophenone, salicylic acid compounds such as phenyl salicylate and 4-t-butylphenyl salicylate, phenylacrylate compounds such as ethyl-2-cyano-3,3-diphenylacrylate, and 2′-ethylhexyl-2-cyano-3,3-diphenylacrylate, benzotriazole compounds such as 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole, and 2-(3-t-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole, coumarin compounds such as 4-methyl-7-diethylamino-1-benzopyran-2-one, thioxanthone compounds such as diethylthioxanthone, stilbene compounds, naphthalic acid compounds, azo dyes, Phthalocyanine blue, phthalocyanine green, iodine green, Victoria blue, naphthalene black, Photopia methyl violet, bromphenol blue and bromcresol green, laser dyes such as Rhodamine G6, Coumarin 500, DCM (4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H pyran)), Kiton Red 620, Pyrromethene 580, or the like. Additionally, one or more coloring agents may be used in combination to provide the desired coloring.

Adhesion additives may also be added to the photoresist 111 in order to promote adhesion between the photoresist 111 and an underlying layer upon which the photoresist 111 has been applied (e.g., the layer to be patterned 109). In an embodiment the adhesion additives include a silane compound with at least one reactive substituent such as a carboxyl group, a methacryloyl group, an isocyanate group and/or an epoxy group. Specific examples of the adhesion components include trimethoxysilyl benzoic acid, γ-methacryloxypropyl trimethoxy silane, vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanatepropyl triethoxy silane, γ-glycidoxypropyl trimethoxy silane, β-(3,4-epoxycyclohexyl)ethyl trimethoxy silane, benzimidazoles and polybenzimidazoles, a lower hydroxyalkyl substituted pyridine derivative, a nitrogen heterocyclic compound, urea, thiourea, 8-oxyquinoline, 4-hydroxypteridine and derivatives, 1,10-phenanthroline and derivatives, 2,2′-bipyridine and derivatives, benzotriazoles; organophosphorus compounds, phenylenediamine compounds, 2-amino-1-phenylethanol, N-phenylethanolamine, N-ethyldiethanolamine, N-ethylethanolamine and derivatives, benzothiazole, and a benzothiazoleamine salt having a cyclohexyl ring and a morpholine ring, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, vinyl trimethoxysilane, combinations of these, or the like.

Surface leveling agents may additionally be added to the photoresist 111 in order to assist a top surface of the photoresist 111 to be level so that impinging light will not be adversely modified by an unlevel surface. In an embodiment surface leveling agents may include fluoroaliphatic esters, hydroxyl terminated fluorinated polyethers, fluorinated ethylene glycol polymers, silicones, acrylic polymer leveling agents, combinations of these, or the like.

In an embodiment the polymer resin and the PACs, along with any desired additives or other agents, are added to the solvent for application. Once added, the mixture is then mixed in order to achieve an even composition throughout the photoresist 111 in order to ensure that there are no defects caused by an uneven mixing or non-constant composition of the photoresist 111. Once mixed together, the photoresist 111 may either be stored prior to its usage or else used immediately.

Once ready, the photoresist 111 may be utilized by initially applying the photoresist 111 onto the layer to be patterned 109. The photoresist 111 may be applied to the layer to be patterned 109 so that the photoresist 111 coats an upper exposed surface of the layer to be patterned 109, and may be applied using a process such as a spin-on coating process, a dip coating method, an air-knife coating method, a curtain coating method, a wire-bar coating method, a gravure coating method, a lamination method, an extrusion coating method, combinations of these, or the like. In an embodiment the photoresist 111 may be applied such that it has a thickness over the surface of the layer to be patterned 109 of between about 10 nm and about 300 nm, such as about 150 nm.

Once the photoresist 111 has been applied to the semiconductor substrate, a pre-bake of the photoresist 111 is performed in order to cure and dry the photoresist 111 prior to exposure to finish the application of the photoresist 111. The curing and drying of the photoresist 111 removes the solvent component while leaving behind the polymer resin, the PACs, cross-linking agents, and the other chosen additives. In an embodiment the pre-bake may be performed at a temperature suitable to evaporate the solvent, such as between about 40° C. and 150° C., although the precise temperature depends upon the materials chosen for the photoresist 111. The pre-bake is performed for a time sufficient to cure and dry the photoresist 111, such as between about 10 seconds to about 5 minutes, such as about 90 seconds.

FIG. 2 illustrates an exposure of the photoresist 111 to form an exposed region 201 and an unexposed region 203 within the photoresist 111. In an embodiment the exposure may be initiated by placing the semiconductor device 100 and the photoresist 111, once cured and dried, into an imaging device 200 for exposure. The imaging device 200 may comprise a support plate 205, an energy source 207, a patterned mask 209 between the support plate 205 and the energy source 207, and optics 213. In an embodiment the support plate 205 is a surface to which the semiconductor device 100 and the photoresist 111 may be placed or attached to and which provides support and control to the substrate 101 during exposure of the photoresist 111. Additionally, the support plate 205 may be movable along one or more axes, as well as providing any desired heating or cooling to the substrate 101 and photoresist 111 in order to prevent temperature gradients from affecting the exposure process.

In an embodiment the energy source 207 supplies energy 211 such as light to the photoresist 111 in order to induce a reaction of the PACs, which in turn reacts with the polymer resin to chemically alter those portions of the photoresist 111 to which the energy 211 impinges. In an embodiment the energy 211 may be electromagnetic radiation, such as g-rays (with a wavelength of about 436 nm), i-rays (with a wavelength of about 365 nm), ultraviolet radiation, far ultraviolet radiation, x-rays, electron beams, or the like. The energy source 207 may be a source of the electromagnetic radiation, and may be a KrF excimer laser light (with a wavelength of 248 nm), an ArF excimer laser light (with a wavelength of 193 nm), a F₂ excimer laser light (with a wavelength of 157 nm), or the like, although any other suitable source of energy 211, such as mercury vapor lamps, xenon lamps, carbon arc lamps or the like, may alternatively be utilized.

The patterned mask 209 is located between the energy source 207 and the photoresist 111 in order to block portions of the energy 211 to form a patterned energy 215 prior to the energy 211 actually impinging upon the photoresist 111. In an embodiment the patterned mask 209 may comprise a series of layers (e.g., substrate, absorbance layers, anti-reflective coating layers, shielding layers, etc.) to reflect, absorb, or otherwise block portions of the energy 211 from reaching those portions of the photoresist 111 which are not desired to be illuminated. The desired pattern may be formed in the patterned mask 209 by forming openings through the patterned mask 209 in the desired shape of illumination.

Optics (represented in FIG. 2 by the trapezoid labeled 213) may be used to concentrate, expand, reflect, or otherwise control the energy 211 as it leaves the energy source 207, is patterned by the patterned mask 209, and is directed towards the photoresist 111. In an embodiment the optics 213 comprise one or more lenses, mirrors, filters, combinations of these, or the like to control the energy 211 along its path. Additionally, while the optics 213 are illustrated in FIG. 2 as being between the patterned mask 209 and the photoresist 111, elements of the optics 213 (e.g., individual lenses, mirrors, etc.) may also be located at any location between the energy source 207 (where the energy 211 is generated) and the photoresist 111.

In an embodiment the semiconductor device 100 with the photoresist 111 is placed on the support plate 205. Once the pattern has been aligned to the semiconductor device 100, the energy source 207 generates the desired energy 211 (e.g., light) which passes through the patterned mask 209 and the optics 213 on its way to the photoresist 111. The patterned energy 215 impinging upon portions of the photoresist 111 induces a reaction of the PACs within the photoresist 111. The chemical reaction products of the PACs' absorption of the patterned energy 215 (e.g., acids/bases/free radicals) then reacts with the polymer resin, chemically altering the photoresist 111 in those portions that were illuminated through the patterned mask 209.

In a specific example in which the patterned energy 215 is a 193 nm wavelength of light, the PAC is a photoacid generator, and the group to be decomposed is a carboxylic acid group on the hydrocarbon structure and a cross linking agent is used, the patterned energy 215 will impinge upon the photoacid generator and the photoacid generator will absorb the impinging patterned energy 215. This absorption initiates the photoacid generator to generate a proton (e.g., a H+ ion) within the photoresist 111. When the proton impacts the carboxylic acid group on the hydrocarbon structure, the proton will react with the carboxylic acid group, chemically altering the carboxylic acid group and altering the properties of the polymer resin in general. The carboxylic acid group will then react with the cross-linking agent to cross-link with other polymer resins within the photoresist 111.

Optionally, the exposure of the photoresist 111 may occur using an immersion lithography technique. In such a technique an immersion medium (not individually illustrated in FIG. 2) may be placed between the imaging device 200 (and particularly between a final lens of the optics 213) and the photoresist 111. With this immersion medium in place, the photoresist 111 may be patterned with the patterned energy 215 passing through the immersion medium.

In this embodiment a protective layer (also not individually illustrated in FIG. 2) may be formed over the photoresist 111 in order to prevent the immersion medium from coming into direct contact with the photoresist 111 and leaching or otherwise adversely affecting the photoresist 111. In an embodiment the protective layer is insoluble within the immersion medium such that the immersion medium will not dissolve it and is immiscible in the photoresist 111 such that the protective layer will not adversely affect the photoresist 111. Additionally, the protective layer is transparent so that the patterned energy 215 may pass through the protective layer.

In an embodiment the protective layer comprises a protective layer resin within a protective layer solvent. The material used for the protective layer solvent is, at least in part, dependent upon the components chosen for the photoresist 111, as the protective layer solvent should not dissolve the materials of the photoresist 111 so as to avoid degradation of the photoresist 111 during application and use of the protective layer. In an embodiment the protective layer solvent includes alcohol solvents, fluorinated solvents, and hydrocarbon solvents.

Specific examples of materials that may be utilized for the protective layer solvent include methanol, ethanol, 1-propanol, isopropanol, n-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 3-methyl-1-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, n-hexanol, cyclohecanol, 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, 2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 2-methyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 2,2,3,3,4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 2,2,3,3,4,4,5,5,6,6-decafluoro-1-hexanol, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-diol, 2-fluoroanisole, 2,3-difluoroanisole, perfluorohexane, perfluoroheptane, perfluoro-2-pentanone, perfluoro-2-butyltetrahydrofuran, perfluorotetrahydrofuran, perfluorotributylamine, perfluorotetrapentylamine, toluene, xylene and anisole, and aliphatic hydrocarbon solvents, such as n-heptane, n-nonane, n-octane, n-decane, 2-methylheptane, 3-methylheptane, 3,3-dimethylhexane, 2,3,4-trimethylpentane, combinations of these, or the like.

The protective layer resin may comprise a protective layer repeating unit. In an embodiment the protective layer repeating unit may be an acrylic resin with a repeating hydrocarbon structure having a carboxyl group, an alicyclic structure, an alkyl group having one to five carbon atoms, a phenol group, or a fluorine atom-containing group. Specific examples of the alicyclic structure include a cyclohexyl group, an adamantyl group, a norbornyl group, a isobornyl group, a tricyclodecyl group, a tetracyclododecyl group, and the like. Specific examples of the alkyl group include an n-butyl group, an isobutyl group, or the like. However, any suitable protective layer resin may alternatively be utilized.

The protective layer composition may also include additional additives to assist in such things as adhesion, surface leveling, coating, and the like. For example, the protective layer composition may further comprise a protective layer surfactant, although other additives may also be added, and all such additions are fully intended to be included within the scope of the embodiment. In an embodiment the protective layer surfactant may be a alkyl cationic surfactant, an amide-type quaternary cationic surfactant, an ester-type quaternary cationic surfactant, an amine oxide surfactant, a betaine surfactant, an alkoxylate surfactant, a fatty acid ester surfactant, an amide surfactant, an alcohol surfactant, an ethylenediamine surfactant, or a fluorine- and/or silicon-containing surfactant.

Specific examples of materials that may be used for the protective layer surfactant include polyoxyethylene alkyl ethers, such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether and polyoxyethylene oleyl ether; polyoxyethylene alkyl aryl ethers, such as polyoxyethylene octyl phenol ether and polyoxyethylene nonyl phenol ether; polyoxyethylene-polyooxypropylene block copolymers; sorbitan fatty acid esters, such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate and sorbitan tristearate; and polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate and polyoxyethylene sorbitan tristearate.

Prior to application of the protective layer onto the photoresist 111, the protective layer resin and desired additives are first added to the protective layer solvent to form a protective layer composition. The protective layer solvent is then mixed to ensure that the protective layer composition has a consistent concentration throughout the protective layer composition.

Once the protective layer composition is ready for application, the protective layer composition may be applied over the photoresist 111. In an embodiment the application may be performed using a process such as a spin-on coating process, a dip coating method, an air-knife coating method, a curtain coating method, a wire-bar coating method, a gravure coating method, a lamination method, an extrusion coating method, combinations of these, or the like. In an embodiment the photoresist 111 may be applied such that it has a thickness over the surface of the photoresist 111 of about 100 nm.

After the protective layer composition has been applied to the photoresist 111, a protective layer pre-bake may be performed in order to remove the protective layer solvent. In an embodiment the protective layer pre-bake may be performed at a temperature suitable to evaporate the protective layer solvent, such as between about 40° C. and 150° C., although the precise temperature depends upon the materials chosen for the protective layer composition. The protective layer pre-bake is performed for a time sufficient to cure and dry the protective layer composition, such as between about 10 seconds to about 5 minutes, such as about 90 seconds.

Once the protective layer has been placed over the photoresist 111, the semiconductor device 100 with the photoresist 111 and the protective layer are placed on the support plate 205, and the immersion medium may be placed between the protective layer and the optics 213. In an embodiment the immersion medium is a liquid having a refractive index greater than that of the surrounding atmosphere, such as having a refractive index greater than 1. Examples of the immersion medium may include water, oil, glycerine, glycerol, cycloalkanols, or the like, although any suitable medium may alternatively be utilized.

The placement of the immersion medium between the protective layer and the optics 213 may be done using, e.g., an air knife method, whereby fresh immersion medium is applied to a region between the protective layer and the optics 213 and controlled using pressurized gas directed towards the protective layer to form a barrier and keep the immersion medium from spreading. In this embodiment the immersion medium may be applied, used, and removed from the protective layer for recycling so that there is fresh immersion medium used for the actual imaging process.

However, the air knife method described above is not the only method by which the photoresist 111 may be exposed using an immersion method. Any other suitable method for imaging the photoresist 111 using an immersion medium, such as immersing the entire substrate 101 along with the photoresist 111 and the protective layer, using solid barriers instead of gaseous barriers, or using an immersion medium without a protective layer, may also be utilized. Any suitable method for exposing the photoresist 111 through the immersion medium may be used, and all such methods are fully intended to be included within the scope of the embodiments.

For example, in a particular embodiment in which the PAC is a photoacid generator and the group which will decompose is an acid labile group, the impinging patterned energy 215 will initiate the photoacid generators to generate, e.g., a acid in the form of a hydrogen proton (H⁺). The hydrogen atoms generated will then react with the acid labile group in the polymer resin, removing portions or all of the acid labile group, and modifying the chemical structure of the reacted polymer resin, leading to a change in the solubility of the polymer resin. In embodiments in which the cross-linking agent is used, the generated acids will also initiate the cross-linking agents to react with the polymer resins, cross-linking the polymer resins to each other and increasing the molecular weight of the resulting polymer.

After the photoresist 111 has been exposed to the patterned energy 215, a post-exposure baking may be used in order to assist in the generating, dispersing, and reacting of the acid/base/free radical generated from the impingement of the patterned energy 215 upon the PACs during the exposure. Such assistance helps to create or enhance chemical reactions which generate chemical differences between the exposed region 201 and the unexposed region 203 within the photoresist 111. These chemical differences also caused differences in the solubility between the exposed region 201 and the unexposed region 203. In an embodiment this post-exposure baking may occur at temperatures of between about 50° C. and about 160° C. for a period of between about 40 seconds and about 120 seconds.

FIGS. 3A-3B illustrate a development of the photoresist 111 with the use of a developer 301 after the photoresist 111 has been exposed. After the photoresist 111 has been exposed and the post-exposure baking has occurred, the photoresist 111 may be developed using either a positive tone developer or a negative tone developer, depending upon the desired pattern for the photoresist 111. In an embodiment in which the exposed region 201 of the photoresist 111 is desired to be removed to form a positive tone, a positive tone developer such as a basic aqueous solution may be utilized to remove those portions of the photoresist 111 which were exposed to the patterned energy 215 and which have had their solubility modified and changed through the chemical reactions. Such basic aqueous solutions may include tetra methyl ammonium hydroxide (TMAH), tetra butyl ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium silicate, sodium metasilicate, aqueous ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine, dibutylamine, monoethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, diethylaminoethanol, potassium metasilicate, sodium carbonate, tetraethylammonium hydroxide, combinations of these, or the like.

If a negative tone development is desired, an organic solvent or critical fluid may be utilized to remove those portions of the photoresist 111 which were not exposed to the energy and, as such, retain their original solubility. Specific examples of materials that may be utilized include hydrocarbon solvents, alcohol solvents, ether solvents, ester solvents, critical fluids, combinations of these, or the like. Specific examples of materials that can be used for the negative tone solvent include hexane, heptane, octane, toluene, xylene, dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, methanol, ethanol, propanol, butanol, critical carbon dioxide, diethyl ether, dipropyl ether, dibutyl ether, ethyl vinyl ether, dioxane, propylene oxide, tetrahydrofuran, cellosolve, methyl cellosolve, butyl cellosolve, methyl carbitol, diethylene glycol monoethyl ether, acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pyridine, formamide, N,N-dimethyl formamide, or the like.

However, as one of ordinary skill in the art will recognize, the above description of positive tone developers and negative tone developers are only intended to be illustrative and are not intended to limit the embodiments to only the developers listed above. Rather, any suitable type of developer, including acid developers or even water developers, that may be utilized to selectively remove a portion of the photoresist 111 that has a different property (e.g., solubility) than another portion of the photoresist 111, may alternatively be utilized, and all such developers are fully intended to be included within the scope of the embodiments.

In an embodiment in which immersion lithography is utilized to expose the photoresist 111 and a protective layer is utilized to protect the photoresist 111 from the immersion medium, the developer 301 may be chosen to remove not only those portions of the photoresist 111 that are desired to be removed, but may also be chosen to remove the protective layer in the same development step. Alternatively, the protective layer may be removed in a separate process, such as by a separate solvent from the developer 301 or even an etching process to remove the protective layer from the photoresist 111 prior to development.

FIG. 3A illustrates an application of the developer 301 to the photoresist 111 using, e.g., a spin-on process. In this process the developer 301 is applied to the photoresist 111 from above the photoresist 111 while the semiconductor device 100 (and the photoresist 111) is rotated. In an embodiment the developer 301 may be supplied at a flow rate of between about 10 ml/min and about 2000 ml/min, such as about 1000 ml/min, while the semiconductor device 100 is being rotated at a speed of between about 100 rpm and about 3500 rpm, such as about 1500 rpm. In an embodiment the developer 301 may be at a temperature of between about 10° C. and about 80° C., such as about 50° C., and the development may continue for between about 1 minute to about 60 minutes, such as about 30 minutes.

However, while the spin-on method described herein is one suitable method for developing the photoresist 111 after exposure, it is intended to be illustrative and is not intended to limit the embodiments. Rather, any suitable method for development, including dip processes, puddle processes, spray-on processes, combinations of these, or the like, may alternatively be used. All such development processes are fully intended to be included within the scope of the embodiments.

FIG. 3B illustrates a cross-section of the development process in which a positive tone developer is utilized. As illustrated, the developer 301 is applied to the photoresist 111 and dissolves the exposed portion 201 of the photoresist 111. This dissolving and removing of the exposed portion 201 of the photoresist 111 leaves behind an opening within the photoresist 111 that patterns the photoresist 111 in the shape of the patterned energy 215, thereby transferring the pattern of the patterned mask 209 to the photoresist 111.

FIGS. 4A and 4B illustrate the photoresist 111 after the developer has been removed, with FIG. 4B illustrating a close-up, expanded view that illustrates a portion of the atoms (not drawn to scale) along the various surfaces within the dashed region 400 in FIG. 4A. In an embodiment in which a spin-on process is utilized, the developer 301 may be removed by stopping the flow of developer 301 to the photoresist 111 and allowing the photoresist 111 to spin-dry, although any suitable method to remove the developer 301 may alternatively be utilized.

However, while the removal of the developer 301 also removes any of the photoresist 111 that had been absorbed by the developer 301, a residue 401 may be left behind on the photoresist 111. This residue 401 may be the result of side products, unreacted groups, or unfinished reactions between the PACs, the polymer resin, and/or the cross-linking agent within the photoresist 111. This residue 401, if left untreated such that it remains on the surface of the photoresist 111, will interfere with further processing of the semiconductor device 100, leading to an increase in defects during processing and an overall decrease in yield.

FIG. 4B illustrates a closer view of the residue 401, which may comprise one or more of the hydrocarbon structures of the polymer resin. Remaining on the hydrocarbon structure is one or more unreacted groups (represented in FIG. 4B by the square labeled 402) that were supposed to decompose but that remain unreacted. This may have occurred because the groups which will decompose on the repeating units (described above with respect to FIG. 1) did not react with the acid/base/free radical that was generated by the PACs, causing hydrophobic acid leaving groups (e.g., cycloalkane or adamantine) to remain and cause the hydrocarbon structure to be insoluble in the developer.

Alternatively, in some cases the groups which will decompose may partially but not fully react with the acid/base/free radical generated by the PACs, causing an incomplete reaction that leaves behind a partially reacted group (represented in FIG. 4B by the triangle labeled 404), such as a hydrophilic de-protected acid leaving group. Such incomplete reactions can cause the residue 401 to become only semi-soluble in the developer 301 or else remain completely insoluble in the developer 301, thereby affecting the ability of the developer 301 to remove the polymer resin, resulting in the residue 401. In a particular embodiment in which the acid leaving group comprises a carboxyl group 405 incorporated into the structure prior to exposure, a reaction with the acid/base/free radical may remove a portion of the structure but not remove the carboxyl group 405, which will remain bonded to the polymer resin in the residue 401.

Given these unreacted or incompletely reacted groups that remain on the residue 401, the residue 401 easily redeposits on the photoresist 111, where the presence of the residue 401 may interfere with the further processing of the semiconductor device 100. Additionally, given the groups that may be left on the residue (e.g., the OH group in the carboxylic group) and the groups that may be present on the surface of the photoresist 111 (e.g., the OH group on the photoresist 111), there is also hydrogen bonding (represented by the arrow in FIG. 4B labeled 403) that occurs between the residue 401 and the surface of the photoresist 111. This hydrogen bonding 403 impedes the removal of the residue 401 using cleaning processes. As such, neutral or acidic water washing used as a way of removing and cleaning the photoresist 111 after development is insufficient to remove the residue 401 that may have formed and which will continue to cause defects during further processing.

As such, FIGS. 5A-5C illustrate the beginning of a cleaning process that will aid in the removal of the residue 401, with FIG. 5A illustrating an application of cleaning materials 502, FIG. 5B illustrating a cross-section view of a start of the cleaning process, and FIG. 5C illustrating a close-up view of representative atoms along the residue 401 and the surface of the photoresist 111. In an embodiment the cleaning materials 502 may be chosen in order to provide an alkaline environment 500 for the cleaning process and may, for example, comprise a neutral solvent 501 along with an alkaline chemical 503 in order to generate and maintain the alkaline environment 500.

In an embodiment the neutral solvent 501 may be water, such as de-ionized water that may be utilized for removing any left-over developer 301 or residue 401 from the surface of the photoresist 111. The de-ionized water may optionally include carbon dioxide dissolved into the de-ionized water. However, any suitable neutral solvent 501 may alternatively be utilized. In an embodiment the neutral solvent may be applied to the photoresist 111 using, e.g., a spin-coating method at a flow rate between about 100 ml/min to about 2000 ml/min.

Additionally, in order to form the alkaline environment 500, the alkaline chemical 503 is also applied to the photoresist 111 along with the neutral solvent 501 in order to raise the pH of the neutral solvent 501 and form the alkaline environment 500. In an embodiment the alkaline chemical 503 is any chemical that may be used to adjust the pH of the neutral solvent 501 upwards from neutral. In an embodiment in which the developer 301 used to develop the photoresist 111 is an alkaline developer, the developer 301 used to develop the photoresist 111 may be used as the alkaline chemical 503, although any other alkaline chemical, such as guanidinium, sodium hydroxide, calcium hydroxide, combinations of these, or the like may alternatively be used. The alkaline chemical 503 may be applied to the photoresist 111 at the same time as the neutral solvent 501 and at a flow rate, e.g., of between about 10 ml/min to about 2000 ml/min.

The relative flow rates of the neutral solvent 501 to the alkaline chemical 503 may be modified in order to provide the desired alkalinity for the alkaline environment 500. In an embodiment the alkaline environment 500 may be held to have a pH range of greater than 7 and less than about 12. For example, in an embodiment in which the neutral solvent is deionized water and the alkaline chemical is the alkaline developer TMAH 2.38%, to achieve a desired pH of 10, the flow rate of the neutral solvent 501 may be 100 ml/min˜2000 ml/min while the flow rate of the alkaline chemical 503 may be 10 ml/min˜2000 ml/min.

Additionally, while the neutral solvent 501 and the alkaline chemical 503 are illustrated in FIG. 5A as being dispersed onto the photoresist 111 separately, this is merely one example of the way the neutral solvent 501 and the alkaline chemical 503 may be applied. Alternatively, the neutral solvent 501 and the alkaline chemical 503 may be pre-mixed into a single solution (not illustrated) and the single solution may then be applied to the photoresist 111, or else the neutral solvent 501 and the alkaline chemical 503 may be mixed in-line right before their application onto the photoresist 111. Any suitable method of forming the alkaline environment 500 on the photoresist 111 may alternatively be used, and all such methods are fully intended to be included within the scope of the embodiments.

FIG. 5B illustrates a cross-sectional view of the alkaline environment 500 present on the surface of the photoresist 111 and on the surface of the residue 401. As illustrated, the alkaline environment 500 covers the surface of the photoresist 111 and the residue 401, thereby encompassing both the surface of the photoresist 111 and the surfaces of the residue 401 and able to interact with the atoms present on both the surface of the photoresist 111 and the surface of the residue 401.

FIG. 5C illustrates a close-up, expanded view of the surfaces of the photoresist 111 and the residue 401, and also illustrates representative atoms along each of the surfaces while the surfaces are within the alkaline environment 500. For example, the surface of the photoresist 111, instead of being terminated with OH groups as described above in FIG. 4B, has been modified by the alkaline environment 500 to remove the hydrogen atom and leave the surface of the photoresist 111 terminated with an O⁻ atom. Similarly, any leftover OH groups that may be present along the residue 401 (e.g., the OH group located on the carboxylic group 405 of the partially reacted group 404) may be modified by removing the hydrogen atom and terminating the surface of the residue 401 with an O⁻ atom.

By modifying the terminating groups on both the surface of the photoresist 111 as well as groups located along the surface of the residue 401, both the surface of the photoresist 111 and the surface of the residue 401 will have groups with negative charges. In the particular embodiment described above in which the photoresist 111 initially has a surface of OH groups and the residue 401 has carboxylic acids groups, both the surface of the photoresist 111 and the surface of the residue 401 in the alkaline environment 500 will have O⁻ groups. As such, the original hydrogen bonding 403 (see FIG. 4) that attracted the residue 401 to the surface of the photoresist 111 and made it more difficult to remove the residue 401 is removed.

Additionally, given that both the surface of the photoresist 111 and the surface of the residue 401 have a negative charge, the negative charges along both surfaces will repulse the other surface, causing a repulsive Coulomb force (represented in FIG. 5C by the arrow labeled 507) between the residue 401 and the photoresist 111. This repulsive force 507, instead of making it harder to remove the residue 401, will actually assist in the removal of the residue 401 from the surface of the photoresist 111 as well as de-charge the positive charging particle from its low resistance of solution. As such, the cleaning of the residue 401 from the photoresist 111 is more easily performed, leading to an overall cleaner photoresist 111, which will lead to fewer processing defects and a larger overall yield.

However, adding the alkaline chemical 503 to the neutral solvent 501 is not the only method by which the residue 401 and the surface of the photoresist 111 may be placed into the alkaline environment 500. In another embodiment the alkaline environment 500 may be created using a Standard Clean (SC)-1 cleaning process to remove the residue 401 and maintain the alkaline environment 500. In an embodiment in which the SC-1 cleaning process is used, the photoresist 111 is exposed to a solution of ammonium hydroxide (NH₄OH), hydrogen peroxide (H₂O₂), and water in a suitable ratio to maintain the alkaline environment 500 to a desired pH level. In a particular embodiment the ratio may be a 1:1:5 ratio, although any suitable ratio may alternatively be utilized, and the ratios may be tuned to the desired pH level.

The cleaning solution of the SC-1 cleaning process may be applied to the photoresist 111 and the residue 401 using, e.g., a spin-on method whereby the cleaning solution of the SC-1 cleaning process is dispensed onto the photoresist 111 at a flow rate of between about 10 ml/min and about 2000 ml/min, such as about 1000 ml/min, while the substrate 101 and the photoresist 111 are spun at a speed of between about 500 rpm and about 3000 rpm, such as about 1500 rpm. However, any suitable method of applying the cleaning solution of the SC-1 cleaning process, such as a dip method or a spray-on method, may alternatively be utilized, and all such methods are fully intended to be included within the scope of the embodiments.

When the cleaning solution of the SC-1 cleaning process comes into contact with the photoresist 111 and the residue 401, the alkaline environment 500 of the cleaning solution of the SC-1 cleaning process will react with the groups in a similar fashion as described above with respect to the embodiment using an alkaline developer. In particular, the alkaline environment 500 will react such that the surface of the photoresist 111 and the surface of the residue 401 have O⁻ groups which generate the repulsive force 507 and repel the residue 401 from the surface of the photoresist 111. As such, the alkaline environment 500 assists in the removal of the residue 401, helping to decrease defects and increase the overall yield of the manufacturing process.

Furthermore, while two embodiments of the alkaline environment 500 (a mixture of the alkaline developer and deionized water and an SC-1 cleaning process) have been described in detail above, one of ordinary skill in the art will recognize that these two embodiments are intended as being illustrative and the alkaline environment 500 is not intended to be limited to these two embodiments. Rather, any suitable alkaline environment that can help to modify the surface of the photoresist 111 and/or the surface of the residue 401 to assist in the removal of the residue may alternatively be utilized, and all such alkaline environments are fully intended to be included within the scope of the embodiments.

Additionally, a cleaning surfactant may be utilized along with the cleaning materials 502 or the SC-1 cleaning solution to create the alkaline environment 500. In an embodiment the cleaning surfactant has hydrophobic groups which, once the cleaning surfactant penetrates to the surface of the residue 401, will adhere to and interfere with the hydrophobic groups of the polymer resin and its remaining groups within the residue 401. This interference from the cleaning surfactant helps to make the residue 401 easier to dissolve in the cleaning materials 502 or the SC-1 cleaning solution. In an embodiment the cleaning surfactant may have the following structure:

where, n may be from between 1 to 15 and the R₁ and R₂ groups may be an alkyl group hydrogen attached to the hydrocarbon with a carbon number between 1 and 10. The alkyl group may be either straight, branched, or have a cyclic structure, and may be single, double, or triple bonded alkyl structure. The alkyl group may also comprise hetero atoms such as nitrogen, oxygen, or fluorine. R₁ and R₂ may also comprise a nitro- or a sulfonic-group.

In an embodiment in which the cleaning materials 502 are dispensed onto the photoresist 111 individually, the cleaning surfactant may be dispensed at a flow rate of between about 10 ml/min and about 2000 ml/min, such as about 300 ml/min. However, in an embodiment in which the cleaning materials 502 are pre-mixed (either in-line or in a batch process), the cleaning surfactant may have a concentration within the cleaning solution of between about 0.001 wt % and about 40 wt %, such as about 0.1 wt %.

Other additives may also be mixed in with the cleaning materials 502 or the SC-1 cleaning solution. For example, a cleaning additive may be added to protect the photoresist 111 as well as to protect the cleaning surfactant. In an embodiment the cleaning additive is used to chemically react with the hydrophilic structure of the photoresist 111 in order to terminate the photoresist 111 with a hydrophobic termination, thereby making dissolution of the photoresist 111 harder. In an embodiment the cleaning additive may have the following structure:

where the R₁, R₂, and R₃ groups may contain alkyl functional structures with straight, branched, or cyclic structures, and may be single, double or tripled bonded structures. The alkyl functional structure may comprise hydrogen, and may be a hydrocarbon chain with from one to ten carbons. At least one of the R₁, R₂, and R₃ groups may comprise an amine structure. The R₁, R₂, and R₃ groups may also comprise at least one substituted nitrogen, oxygen, or fluorine atom. Additionally, the R₁, R₂, and R₃ groups may also contain nitro- or sulfonic-groups.

In an embodiment in which the cleaning materials 502 are dispensed onto the photoresist 111 individually, the cleaning additive may be dispensed at a flow rate of between about 10 ml/min and about 2000 ml/min, such as about 200 ml/min. However, in an embodiment in which the cleaning materials 502 are pre-mixed (either in-line or in a batch process), the cleaning additive may have a concentration within the cleaning solution of between about 0.001 wt % and about 40 wt %, such as about 0.1 wt %.

FIGS. 6A and 6B illustrate reductions in defect counts that can be obtained by utilizing the alkaline environment 500 to clean the residue 401 off of the photoresist 111. The test method charted in FIG. 6A, which illustrates a defect comparison test, illustrates a 95% reduction in the defect count from a cleaning performed in a non-alkaline environment to a cleaning performed in an alkaline environment. Similarly, in the test method charted in FIG. 6B, which illustrates a defect comparison test, a 90% reduction in defect counts can be realized. As such, using an alkaline environment 500 to clean the photoresist 111 after development can lead to fewer defects and an overall greater yield for the manufacturing process.

After the residue 401 has been removed from the surface of the photoresist 111, additional processing may be performed on the photoresist 111 to prepare it for use. In an embodiment one such process may be a Finishing-up by Improved Rinse Materials (FIRM) treatment that helps to reduce any pattern collapse that may occur in the photoresist 111. In an embodiment the FIRM treatment rinses the photoresist 111 with a mixture of deionized water and surfactants in order to reduce the surface tension of the rinse during, e.g., a spin dry process, thereby reducing the stressed generated by the rinsing materials during the spin drying process.

In an embodiment the surfactants mixed with the deionized water may be surfactants such as alkyl carboxylates, pentaethylene glycol, or perfluorooctanesulfonic acid. The surfactants may be mixed with the deionized water so that the surfactants have a concentration of between about 0.001 wt % and about 40 wt %, such as about 0.1 wt %, and may be applied to the photoresist 111 using, e.g., a spin-on process wherein the mixture is flowed onto the photoresist 111 at a flow rate of between about 10 ml/min and about 2000 ml/min, such as about 300 ml/min, while the photoresist 111 is rotated at a speed of between about 500 rpm and about 3000 rpm, such as about 1500 rpm. Once the FIRM treatment is completed, the photoresist 111 may be dried using, e.g., a spin drying process.

Once the photoresist 111 is rinsed and dried, further processing may be performed on the layer to be patterned 109 while the photoresist 111 is in place. As one example, a reactive ion etch or other etching process may be utilized, to transfer the pattern of the photoresist 111 to the underlying layer to be patterned 109. Alternatively, in an embodiment in which the layer to be patterned 109 is a seed layer, the layer to be patterned 109 may be plated in order to form, e.g., a copper pillar, or other conductive structure in the opening of the photoresist 111. Any suitable processing, whether additive or subtractive, that may be performed while the photoresist 111 is in place may be performed, and all such additional processing are fully intended to be included within the scope of the embodiments.

In accordance with an embodiment, a method of manufacturing a semiconductor device comprises developing a photoresist over a substrate and cleaning the photoresist after the developing, the cleaning the photoresist comprising applying an alkaline environment to a surface of the photoresist.

In accordance with another embodiment, a method of manufacturing a semiconductor device comprising removing a developer from a photoresist, the removing the developer leaving behind a residue, is provided. The residue is removed from the photoresist, the removing the residue further comprising treating a surface of the residue to have a first charge and treating a surface of the photoresist to have the first charge.

In accordance with yet another embodiment, a method of manufacturing a semiconductor device comprising applying a photoresist to a substrate and developing the photoresist to form a patterned photoresist is provided. The patterned photoresist is cleaned using an alkaline environment, wherein the alkaline environment chemically modifies a top surface of the photoresist.

Although the present embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. For example, the precise chemicals utilized in the alkaline environment may be modified as suitable to maintain the alkaline environment, while the precise processes (such as method of dispensing) may be changed without departing from the scope of the embodiments.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

What is claimed is:
 1. A method of manufacturing a semiconductor device, the method comprising: developing a photoresist over a substrate, wherein after the developing the photoresist a surface of the photoresist is hydrogen bonded to residue; and removing the hydrogen bonding by applying an alkaline environment to the surface of the photoresist.
 2. The method of claim 1, wherein the applying the alkaline environment further comprises applying a neutral solvent and an alkaline chemical.
 3. The method of claim 2, wherein the neutral solvent has carbon dioxide dissolved within it.
 4. The method of claim 2, wherein the neutral solvent and the alkaline chemical are applied separately.
 5. The method of claim 2, wherein the neutral solvent and the alkaline chemical are mixed prior to the applying the alkaline environment.
 6. The method of claim 2, wherein the alkaline environment further comprises a cleaning surfactant.
 7. The method of claim 6, wherein the applying the alkaline environment further comprises applying a cleaning additive.
 8. The method of claim 2, wherein the alkaline chemical comprises guanidinium, sodium hydroxide, or calcium hydroxide.
 9. A method of manufacturing a semiconductor device, the method comprising: removing a developer from a photoresist, the removing the developer leaving behind a residue; and generating a repulsive force between the photoresist and the residue without removing the photoresist.
 10. The method of claim 9, wherein the generating the repulsive force between the photoresist and the residue further comprises applying a solution with a pH greater than 7 onto a surface of the photoresist.
 11. The method of claim 10, wherein the solution further comprises: a neutral solvent; and an alkaline component.
 12. The method of claim 11, wherein the alkaline component comprises guanidinium.
 13. The method of claim 11, wherein the alkaline component comprises sodium hydroxide.
 14. The method of claim 11, wherein the alkaline component comprises calcium hydroxide.
 15. A method of manufacturing a semiconductor device, the method comprising: applying a photoresist to a substrate; developing the photoresist to form a patterned photoresist; and modifying terminal groups of the patterned photoresist using an alkaline environment, wherein the alkaline environment is applied by simultaneously applying: a neutral solvent with dissolved carbon dioxide; and an alkaline chemical, wherein the alkaline chemical is applied to the patterned photoresist separately from the neutral solvent.
 16. The method of claim 15, further comprising modifying terminal groups of a residue located on the patterned photoresist.
 17. The method of claim 16, wherein the modifying the terminal groups of the patterned photoresist modifies the terminal groups of the patterned photoresist to have a first charge and the modifying the terminal groups of the residue modifies the terminal groups of the residue to have the first charge.
 18. The method of claim 16, further comprising obtaining a desired pH of the alkaline environment by setting a relative flow rate between the neutral solvent and the alkaline chemical.
 19. The method of claim 15, wherein the alkaline environment is applied by simultaneously applying a cleaning surfactant with the neutral solvent and the alkaline chemical.
 20. The method of claim 19, wherein the alkaline environment is applied by simultaneously applying a cleaning additive with the neutral solvent and the alkaline chemical. 